/Engine/Source/Runtime/Analytics/AnalyticsET/Public/AnalyticsFlowTracker.h
Start a new flow step and add it to a specific flow context by GUID
[FGuid](API\Runtime\Core\Misc\FGuid) StartSubFlow ( const [FName](API\Runtime\Core\UObject\FName) & SubFlowName, const [FGuid](API\Runtime\Core\Misc\FGuid) & FlowGuid )